pons asi·no·rum \-ˌasənˈōrəm\noun (-s) Etymology: New Latin, asses' bridge 1. a.: asses' bridge b.: a critical test of ability imposed upon the inexperienced or ignorant < those who have passed the pons asinorum in the inner life — George Santayana > 2.: a geometrical figure attributed to Petrus Tartaretus (fl. 1480) used to show the various relations of the middle terms of syllogisms